1. Field of the Invention
This invention relates to improvements in an engine cooling arrangement forming part of a cooling system of an internal combustion engine, and more particularly to such an arrangement including a coolant pump and a thermostat for controlling flow of coolant.
2. Description of the Prior Art
Automotive internal combustion engines are usually provided with an engine cooling system including a coolant pump and a thermostat for thermally controlling coolant flow through a radiator. A variety of engine cooling systems have been proposed and put into practical use. One of them is as shown in FIG. 1, in which a thermostat 1 is installed to a transmission while a coolant pump 2 is installed at the front end section of a cylinder block 3. Coolant from a radiator and that from a heater supplied to the thermostat 1, respectively, through pipes 4 and 5. Heated coolant from a coolant jacket of the cylinder block flows through a conduit 6 to the radiator and through a pipe 7 to the heater. Coolant from the thermostat 1 flows into the coolant pump 2. As shown, a coolant pipe 8 is provided to fluidly connect the thermostat and the coolant pump 2. The reference numeral 9 designates a bypass pipe for fluidly connecting the thermostat 1 and the cylinder block coolant jacket.
With such an arrangement, the thermostat 1 and the coolant pump 2 are separate and independent from each other. This requires the relatively long coolant pipe 8 and bypass pipe 9 and additionally hose clamps and the likes while increasing the number of steps in an assembly process for an engine cooling system.
Another one of the engine cooling systems is as shown in FIG. 2, in which the thermostat 1' and the coolant pump 2' are previously assembled as a unit and installed to the cylinder block. Coolant from the radiator is fed through the pipe 5' to the thermostat 1'. Heated coolant from the cylinder block coolant jacket flows through the conduit 6' and the pipe 7' respectively to the radiator and the heater. Coolant from the heater is fed through the pipe 4' to the thermostat 1'.
In order to obtain the thus previously assembled thermostat 1' and coolant pump 2' as a unit, a core is required for casting a block formed with a coolant passageway communicating the thermostat and the coolant pump. This renders difficult production of the block with aluminum die casting.